I'm a typical liberal alright and find leftists to be laughable. That being said, I don't even think you're 100% wrong on this. Yes Bernie had the better platform in many ways. Biden ran on a surprisingly liberal platform but overall his primary message was "Obama is my friend." The fact that his message worked tells me more about his opponents than him. That first debate, where candidate after candidate teed off on Obama, was a stunning display of twitter brain. Leftism drowns social media discourse/language, and when candidates allow young activists to create their talking points you get the trainwreck we saw. Biden, flaws and all, was a normal breath of fresh air for MOST people. And familiar. I'm not surprised he won at all. And I maintain he was the only person on that stage who would have beaten Trump.
My problem is that I don't want to hear crying from people who played the game 100% wrong. This is math. The delegate situation means you need to either win the south or come. And to do that, you need black voters. Bernie spent two election cycles trying to prove that he could conjure white working class voters and win off that...and it failed miserably. Instead of taking any lessons from that, him and his stans simply got even more unlikable and mean. "I lost because people are stupid" is not a path to success. But then again leftism is not about paths to success or winning. Leftism is about being right. And that's why you'll keep losing.
What a shytty situation. On one hand you have liberals focused on winning, with zero focus on power or doing shyt after winning. On the other hand you have leftists focused on being right, with zero interest in winning.